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Satellite creates best topographic map of the Earth

An instrument aboard the Terra satellite has generated the most complete digital topographic map of the Earth ever made, covering 99% of the planet

The most complete digital topographic map of the Earth has been produced. The map was created using measurements from the ASTER instrument (Advanced Spaceborne Thermal Emission and Reflection Radiometer) aboard the decade-old Terra satellite.

In this 3D visualisation of the data, a natural-colour map is draped over a digital grid of the elevations of the Los Angeles Basin and the surrounding San Gabriel Mountains, giving a detailed view of the contours of the land. Look carefully, and you can spot NASA's Jet Propulsion Laboratory as the light-coloured area at the foot of the mountains in the upper right of the image. (Image: ASTER GDEM/METI/NASA)

The map incorporates more than 1 million digital images and covers 99 per cent of the globe, a substantial increase over previous maps, which surveyed just 80 per cent of the planet. The new map covers latitudes between 83° north and 83° south, resolving patches of land as narrow as 30 metres across – three times the resolution of the next best digital topographical map, which was made by the space shuttle Endeavour during an 11-day mission in 2000.

In this colorised version of the new map, low elevations are shown in purple, medium elevations in green and yellow, and high elevations in orange, red and white. (Image: ASTER GDEM/METI/NASA)

This image shows the peaks and valleys of Death Valley, California, the hottest and most arid place in North America. It features the lowest point in North America, Badwater, which sits 85.5 metres below sea level.

The splash of green in the right foreground is Furnace Creek Ranch, the only part of the valley floor to support year-round vegetation, thanks to a regular supply of water from Furnace Creek. But even the Furnace Creek region is scorchingly hot – in July 1913, it set the record for the highest air temperature – 57° C (134° F) – in the Western hemisphere. (Image: ASTER GDEM/METI/NASA)

The new data set is free and available online. Who will use it? "Everybody," says Michael Abrams of JPL, the US science team leader for the ASTER instrument, which is a joint project of Japan and the US. Topological maps are used variously to help build roads, plan cities, study a region's ecosystems, determine the potential damage from natural disasters such as tsunamis, and help route phone calls to nearby cell phone towers.

To create the new map, the ASTER instrument aboard the Terra satellite took two images every 30 metres. One picture was snapped from directly overhead, while the other was taken looking backwards, over the satellite's shoulder, as it crossed the Earth's surface. The pair of images was then combined for a 3D view. (Illustration: ASTER/METI/NASA)